Automatic injector with needle cover

ABSTRACT

An auto-injector automatically dispenses a predetermined dose of medicament upon activation. The auto-injector includes a needle cover operative to engage an injection site and activate the injector. The needle cover is configured to move from a locked retracted position prior to a medicament dispensing operation to a locked extended position after the medicament dispensing operation. The non-removable needle cover prevents contact with the needle both before and after the medicament dispensing operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 12/258,754,filed Oct. 27, 2008, now U.S. Pat. No. 8,048,035, which is acontinuation-in-part of U.S. patent application Ser. No. 11/095,664,filed Apr. 1, 2005, now U.S. Pat. No. 7,449,012, which claims thebenefit of U.S. Provisional Application No. 60/599,054, filed Aug. 6,2004, the entire contents of each are expressly incorporated herein byreference thereto.

FIELD OF THE INVENTION

The invention relates to an automatic injector or auto-injector fordelivering medicament to an injection site. In particular, the inventionis directed to an auto-injector having a needle cover mechanism toprevent a user from coming into contact with the needle of theauto-injector after use. The needle cover mechanism is held in a lockedposition prior to activation of the auto-injector. After injection, theneedle cover mechanism is held in a locked deployed position such thatthe user cannot access the needle.

The invention is also directed to an auto-injector having a power packcontaining a one-piece molded collet. The molded collet reduces theoverall number of manufactured components while increasing versatility.The molded collet can be used with cartridges of varying sizes,different sued needles and can be used to vary the amount of thedelivered dosage of medicament.

BACKGROUND OF THE INVENTION

An automatic injector or auto-injector is a device designed to allow auser to self-administer a pre-measured dose of a medicament compositionsubcutaneously or intramuscularly, usually in an emergency situation.Automatic injectors are used for example, to treat anaphylactic (severeallergic) reactions and to administer antidotes for certain poisons,such as chemical nerve agents and various drug compositions such asdiazepan.

A typical auto-injector has a housing, inside of which is a cartridge.The cartridge has one or several chambers containing medicamentcompositions or components thereof and is adapted to be attached to aneedle assembly. The cartridge can hold either a pre-mixed liquidmedicament or a solid medicament and as liquid that are mixed prior toinjection. The housing carries an actuation assembly with a storedenergy source, for example, a compressed spring. Activation of theactuation assembly causes a sequence of movements, whereby the needleextends from the auto-injector into the user so that the medicamentcompound is then forced through the needle and into the user. Afterdelivery of the dose of medicament into the injection site the nee cueremains in an extended position. If the auto-injector is of the typedesigned to carry plural components of the medicament composition inseparate, sealed compartments, structure may be included that forces thecomponents to mix when the actuation assembly is activated.

There is a need for an auto-injector having a cover that providesadequate protection from the needle both prior to and after operation ofthe auto-injector. U.S. Pat. No. 5,295,965 to Wilmot et al. discloses anexternal cover member providing sharps protection for an auto-injectorafter use. The cover member is deployed after actuation of theauto-injector such that the user does not view the needle after use. Theposition of the cover member with respect to the auto-injector body isoffset after use such that the needle cannot be redeployed through anopening in the needle cover.

U.S. Pat. No. 6,767,336 to Kaplan discloses a cover for anauto-injector. In an effort to reduce components, Kaplan eliminates anouter housing for the auto-injector. The cover is secured to theexterior of the cartridge holder sleeve. The cartridge holder sleeveincludes several slots, which are sized to receive a latch on the cover.When the auto-injector is actuated, the cartridge within the cartridgeholder sleeve causes the latch to be released from the recess such thatthe cover is free to travel under the bias of the spring. Since thecover disclosed by Kaplan is located on the exterior of the cartridgeholder sleeve, it is possible for the user to grip the cover duringoperation of the auto-injector. As such, the user may prevent thelatches from being released from the respective slots, which couldprevent the cover from being properly deployed. This could impede themovement of the cartridge within the cartridge holder sleeve, whichcould result in the medicament being dispensed through the needle priorto the needle reaching the injection site. To overcome thesedeficiencies, higher trigger forces would be necessary. When the latchesare released during the deployment of the cover, the latches are biasedoutwardly. It is possible for the user to be pinched or otherwiseinjured by this deployment.

If the cover deploys prior to delivery of the drug, a potentially lifethreatening event may arise because the user may not receive the properdose of medicament. There is a need for a secured cover such that itcannot be displaced prior to use of the auto-injector. There is also aneed for a cover that does not impede or adversely impact the operationof the auto-injector in the event it is contacted by the user. It isalso desirable that the cover be locked in an extended position afteruse of the auto-injector so that the needle is not exposed such that aperson cannot be accidentally pricked by the needle. It is alsodesirable to have a cover member having locking and deploymentmechanisms that are protected against contact from the operator toprevent improper deployment of the cover.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to an auto-injector fordispensing a predetermined dosage of a medicament. The medicament may beeither self administered or administered by a caregiver. Theauto-injector includes a housing. The housing is preferably oval orelliptical in shape such that it is more ergonomic. The oval shapeprevents the auto-injector from rolling off a table or flat surface,while providing a larger surface area for printing user instructions. Acartridge container is disposed within the housing. A cartridge isreceived within the cartridge container. The cartridge has at least oneopening therein and contains a medicament. The medicament is rearwardlyconfined by a plunger. The cartridge includes a needle assembly todispense the medicament therethrough. The cartridge is advanced withinthe cartridge container from a stored position to an operation positionwhere the needle extends from the cartridge container such that the doseof medicament can be administered. An actuation assembly or power packprovides a stored energy source that is capable of being released todrive the plunger within the cartridge to dispense the medicamentthrough the needle assembly into the user and allowing the needle to beaccessible on activation.

Another aspect of the auto-injector is the provision of a needle coverreceived within the housing. The needle cover shields the user frominadvertent exposure to the needle after use of the auto-injectorproviding sharps protection. Theoretically, the operation of the needlecover is fail safe because the cover will not deploy until after theneedle penetrates the user. During operation, the needle of thecartridge extends through an opening in the needle cover to permit thedispensing of a dose of medicament. After use of the auto-injector, theneedle cover is held in a locked position to prevent the cover frombeing retracted to expose the needle. According to another aspect of theinvention, the needle cover has a locked retracted position prior toactivation of the auto-injector, thus maintaining a compactconfiguration of the device prior to use. According to another aspect ofthe invention, the actuation forces associated with the auto-injectorare not imparted on the needle cover.

In accordance with another aspect of the present invention, theauto-injector has a first locking assembly that holds the needle coverin the first locked position. The first locking assembly may be locatedon the cartridge container. The first locking assembly may include atleast one locking tooth pivotally connected to the cartridge containeror the needle cover. Each locking tooth releasably engages the needlecover and includes a locking surface constructed and arranged to contacta surface on the needle cover or the cartridge container. Each lockingtooth may be formed as a separate component that is connected to thecontainer or cover. It is contemplated that the locking teeth may beformed as integral pans of the needle cover or cartridge. A spring forceof the locking tooth biases the locking surface into contact with theneedle cover. The spring force may be provided by a spring portion ofthe locking tooth. The spring force may also be provided by a separatespring assembly biasing the locking surface into contact with the needlecover. Each locking tooth is preferably pivotally connected to thecartridge container. Each locking tooth pivots in response to movementof the cartridge within the cartridge container. It is also contemplatedthat the locking teeth can pivot in response to movement of the colletor the power pack. Typically, the locking surface pivots out of contactwith the needle cover when the locking tooth pivots in response to themovement of the cartridge. The spring force and the force exerted by thelocking teeth on the cartridge are controlled such that they negligiblyor minimally impede the motion of the cartridge during the injectionoperation to avoid any premature rupturing of the diaphragm within thecartridge and premature administering of the medicament.

The needle cover is spring biased so that the cover is biased outwardlyfrom the housing to cover the exposed needle after the first lockingassembly is released. In accordance with another aspect of the presentinvention, the auto-injector has a second locking assembly that holdsthe needle cover in the second locked position. The second lockingassembly may be located on the cartridge container, the outer body orthe cover member. The second locking assembly may include at least onelocking arm or wing preferably connected to the cartridge container.Each locking arm is spaced from the cartridge container such that thelocking arm can be temporarily compressed against the cartridgecontainer as the needle cover moves from the first locked position tothe second locked position. Each locking arm has a locking surface toengage the needle cover when the needle cover is in the locked extendedposition. Each locking arm has a thick strut portion and a thin strutportion, wherein the thick strut portion is outwardly curved and thethin strut portion is inwardly curved. This construction maintains thelocking arm in a normal uncompressed state to reduce stress on thecartridge container. This also permits a smooth deployment of the covermember. Furthermore, this arrangement ensures that the thick strutportion will buckle into a stable condition. This creates a strongerlock to prevent the cover member from being moved rearwardly to aretracted position. The inwardly curved nature of the thin strut portionallows the thick portion to buckle in a controlled manner to a stablecondition. Additionally, the outwardly curved shape of the thick strutportion provides for fail safe locking of the cover member in theextended position. In the event that the thin strut breaks, the thickstrut portion will still engage the cover member to maintain it in anextended locked position.

The cartridge container may further include at least one ledge extendingoutwardly therefrom. Each ledge is constructed and arranged to engage anedge of an opening in the needle cover to limit the travel of the needlecover with the respect to the cartridge container when the needle coveris in the extended position. When the ledge on the cartridge containerengages the edge of the opening, the outward travel of the needle coveris limited. The second locking assembly limits the inward travel of theneedle cover. The needle cover and the cartridge container containopenings formed therein. When the openings are aligned prior toactivation of the auto-injector, user can view the contents of thecartridge through the housing and the openings. The housing may betransparent or opaque. When opaque, the housing may contain an openingthat can be aligned with the openings in the needle cover and cartridgecontainer so that the color of the medicament may be checked todetermine whether or not the medicament is suitable for injection. Ifthe medicament is discolored, the user will know not to administer themedicament. When the openings are not aligned after operation of theauto-injector, the user is no longer able to view the contents of thecartridge through the openings providing a visual indication to the userthat the auto-injector has been used.

Another aspect of the present invention is the construction andarrangement of the actuation assembly or power pack, which is mountedwithin the housing adjacent to an open end. A release pin or safe pin isremovably attached to the actuation assembly to prevent inadvertentactuation of the auto-injector when the release pin is in place. A pinor stem on the release pin is received within an opening in theactuation assembly to prevent actuation of the auto-injector. Thisopening in the power pack is spaced from the open end of the housingsuch that the opening is less visible to a user prior to administeringthe drug. This arrangement is provided so that user will not orient theincorrect end of the auto-injector against the injection surface of theuser. The power pack is recessed or spaced from the end of the housing,which provides an indication to the user that pressing the power packwill not operate the auto-injector. The recessed nature of the powerpack serves to hide the release pin hole in the power pack when the useris viewing the instructions on the outer body such that the user doesnot confuse the release pin hole with the opening through which theneedle passes for administering the medicament. The release pin includesat least one tab extending therefrom. The tab is compression fit into acomplimentary recess formed in the actuation assembly to prevent theinadvertent removal of the release pin. The tabs also prevent rotationof the release pin such that the user easily recognizes that the releasepin must be pulled in order to be removed.

The actuation assembly includes an outer body, which is configured toengage the lease pin. The cuter body is constructed to be connected tothe housing. An inner body is operatively coupled to the outer body. Atleast one retention tab on the inner body secures the inner body to theouter body. The inner body is capable of limited movement with respectto the outer body. A collet is operatively coupled to the inner body. Anenergy source is operatively connected to the inner body and the collet.Unlike conventional collets, the collet in the present invention ismolded as a single piece. No spacers or other components are providedbetween the collet and the plunger in the cartridge. This arrangementsimplifies construction. Different sized collets can be produced andinstalled into the actuation assembly, such that only the collet needsto altered when different sized cartridges are used or a different sizeddosage of medicament is to be administered.

BRIEF DESCRIPTION OF THE DRAWINGS

An understanding of the various embodiments invention may be gained byvirtue of the following figures, of which like elements in variousfigures will have common reference numbers, and wherein:

FIG. 1 is a side cross sectional view of the auto-injector according toan embodiment of the present invention;

FIG. 2 is a side cross sectional view of the auto-injector of FIG. 1 inan unactivated state having the release pin in place;

FIG. 3 is a side schematic view of auto-injector in the unactivatedstate of FIG. 2;

FIG. 4 is a side cross sectional view of the auto-injector of FIG. 1having the release pin removed in preparation for activation;

FIG. 5 is a side cross sectional view of the auto-injector of FIG. 1wherein the needle cover spring is in a compressed state;

FIG. 6 is a side schematic view of the auto-injector of FIG. 5;

FIG. 7 is a side cross sectional view of the auto-injector in anactuated state with the needle in a drug delivery position;

FIG. 8 is a side schematic view of the auto-injector of FIG. 7;

FIG. 9 is a side cross sectional view of the auto-injector followingdelivery of the drug wherein the needle cover is in an extendedprotective state;

FIG. 10 is an enlarged view of the locking wings of the cartridgecontainer when the needle cover is in the extended protective state, asshown in FIGS. 9 and 11;

FIG. 11 is a side schematic view of the auto-injector of FIG. 9;

FIG. 12 is a left front schematic view of the auto-injector of FIG. 1having the outer body removed wherein the needle cover is located in aretracted position prior to activation of the auto-injector;

FIG. 13 is an enlarged view of FIG. 12 illustrating the position of thelocking wings of the cartridge container and the locking teeth;

FIG. 14 is a left front schematic view of the auto-injector of FIG. 1having the outer body removed when the needle cover is located in anextended protective position after use of the auto-injector;

FIG. 15 is an enlarged view of FIG. 14 illustrating the position oflocking wings of the cartridge container and the locking teeth;

FIG. 16 is an enlarged cross sectional view illustrating the position ofthe locking teeth when the needle cover is in the extended protectiveposition;

FIG. 17 is a left rear perspective view of the power pack outer body forthe power pack for the auto-injector according to the present invention;

FIG. 18 is a side perspective view of the collet for the power pack forthe auto-injector according to the present invention;

FIG. 19 is a right front perspective view of the power pack inner bodyfor the power pack for the auto-injector according to the presentinvention;

FIG. 20 is a side perspective view of the spring assembly for the powerpack for the auto-injector according to the present invention;

FIG. 21 is a left bottom perspective view of the release pin for theauto-injector according to the present invention;

FIG. 22 is a right bottom perspective view of the power pack of theauto-injector in an assembled state;

FIG. 23 is a side cross sectional view of the power pack of FIG. 22;

FIG. 24 is a top left perspective view of the power pack of FIG. 22having the top portion of the release pin and a peripheral rib of thepower pack outer body removed;

FIG. 25 is a top left perspective view of the power pack of FIG. 22;

FIG. 26 is a top left perspective view of the power pack positionedwithin the outer body having the safe pin removed;

FIG. 27 is left side perspective view of the power pack outer body

FIG. 28 is a partial cross sectional perspective view illustrating theinterior the power pack outer body;

FIG. 29 is a partial cross sectional perspective view illustrating theinterior of the power pack inner body;

FIG. 30 is side perspective view of the power pack inner body;

FIG. 31 is a bottom perspective view of the power pack inner body;

FIG. 32 is a side view of the release pin;

FIG. 33 is another side view of the release pin of FIG. 32 rotated aboutan axis;

FIG. 34 is a bottom perspective view of the safe pin of FIG. 32;

FIG. 35 is a side view of the collet of the power pack;

FIG. 36 is another side view of the collet of FIG. 35 rotated 90° aboutan axis;

FIG. 37 is an enlarged end view of the collet illustrating thestabilizing arch;

FIG. 38 is side perspective view of the needle cover located within theouter body of the auto-injector;

FIG. 39 is a cross sectional view of the cartridge container and needlecover located within the outer body with the power pack removed prior tofinal assembly of the auto-injector;

FIG. 40 is a cross sectional view of the cartridge container and needlecover located within the outer body of FIG. 39 rotated 90° about an axiswith the power pack removed prior to final assembly of theauto-injector;

FIG. 41 is a front left side perspective view of the cartridge containerof the auto-injector;

FIG. 42 is a perspective view of the needle cover spring;

FIG. 43 is a front left side perspective view of the needle cover of theauto-injector;

FIG. 44 is a front left side perspective view of the outer body of theauto-injector;

FIG. 45 is another left side perspective view of the outer body of FIG.44;

FIG. 46 is a partial cross sectional perspective view illustrating theinterior of the outer body;

FIG. 47 is a side view of the outer body;

FIG. 48 is another side view of the outer body of FIG. 47 rotated 90°about an axis;

FIG. 49 is a right rear side perspective view of the cartridge containerof the auto-injector;

FIG. 50 is a side view of the cartridge container;

FIG. 51 is another side view of the cartridge container FIG. 51 rotated90° about an axis;

FIG. 52 is an enlarged side view of the cartridge container illustratedin FIG. 51, wherein the dotted lines illustrate the deflection path ofthe locking wings;

FIG. 53 is a right rear perspective view of the needle cover of theauto-injector;

FIG. 54 is a side view of the needle cover of FIG. 53;

FIG. 55 is a perspective view of the needle cover spring;

FIG. 56 is a right top perspective view of a locking tooth of theauto-injector according to the invention;

FIG. 57 is a left bottom perspective view of the locking tooth of FIG.55;

FIG. 58 is a side view of the locking tooth;

FIG. 59 is a top view of the locking tooth;

FIG. 60 is a side view of an auto-injector prior to use withuser-friendly labeling according to the invention; and

FIG. 61 is a side view of the auto-injector of FIG. 60 after use.

DETAILED DESCRIPTION OF THE INVENTION

It should be appreciated that some of the components described hereinare conventionally known in the broader aspects, as described in U.S.Pat. No. 4,031,893 (“the '893 patent”) hereby incorporated by referencein its entirety, and thus not described in unnecessary detail here. Itshould also be appreciated that known modifications or variations to the'893 patent can apply equally to the auto-injector of the presentinvention as will be described below. These modifications or variationsinclude embodiments described in U.S. Pat. Nos. 4,226,235; 4,329,988;4,394,863; 4,723,937; and U.S. Ser. Nos. 09/985,466; 10/285,692, each ofwhich is incorporated by reference in its entirety for the fullteachings therein.

An auto-injector 100 of the present invention will now be described ingreater detail in connection with FIGS. 1-59. The auto-injector 100includes an outer body 110, a release pin 120, a power pack 130, acartridge container 140, a needle cover 150 and a cartridge 160 housinga dose of medicament. The dose can be stored in liquid or solid form oras a combination of a liquid and a solid that is mixed prior toinjection.

The auto-injector 100 includes an outer body 110 shown in FIGS. 38 and44-48. The outer body 110 has a generally oval or elliptical shape,which is more ergonomic sized to permit easy grasping and use by theuser or caregiver in comparison with a cylindrical body. The generallyoval shape of the outer body 110 prevents the auto-injector 100 frominadvertently rolling or sliding off a flat surface. Furthermore, theoval shape provides a larger print surface for labeling theauto-injector 100 with instructions. The outer body 110 is preferablyformed from a synthetic material such that it can be easily molded. Theouter body 110 can be transparent such that the interior components canbe easily viewed through the outer body 110. With such a construction,the user can view the contents of the cartridge 160 through windows 141a and 141 b in the cartridge container 140 and the needle cover 150 atpredetermined times. It is also contemplated that the outer body 110 canbe opaque such that the interior components are not visible through theouter body 110. It is also contemplated that the outer body 110 has awindow or windows that permit viewing of the components within the outerbody 110. The outer body 110 has an opening 111 formed in one end thatis sized to receive a release pin 120. When in place, the release pin120 prevents inadvertent use or activation of the auto-injector 100. Therelease pin 120 is illustrated in FIGS. 32-34. It is contemplated thatoperating instructions may be printed directly onto the outer body 110.It is also contemplated that a label may be affixed to the outer body110, which may increase the rigidity of the outer body 110. When theouter body 110 includes one or more apertures, the provision of a labelincreases the strength of the outer body 110, which snakes the provisionof additional structural reinforcements unnecessary.

The opening 111 includes side recesses 111 a and 111 b, which extenddownwardly along opposing sides of the outer body 110, shown in FIGS.45, 46 and 48. While two recesses are shown, it is contemplated that asingle recess may be provided or more than two may be provided. Thenumber of recesses will, correspond to the number of tabs. The recesses111 a and 111 b are sized so that they may receive downwardly extendingtabs 121 a and 121 b on the release pin 120. The tabs 121 a and 121 bprevent rotation of the release pin 120 such that the user easilyrecognizes that the release pin 120 is to be pulled rather than rotatedto permit removal of the release pin 120 in order to actuate theauto-injector 100. The tabs 121 a and 121 b are primarily received inretention recesses 235 located on opposing sides of the power pack 130,described in greater detail below. The recesses 111 a and 111 b provideaccess to the tabs 121 in the recesses 235. The tabs 121 a and 121 b arecompression fit onto the power pack 130 to prevent inadvertent removal.To release the pin 120, the operator compresses or pinches the tabs 121to dislodge the edges of the tabs 121 from the recesses 235 such thatthe pin 120 can then be pulled/removed from the power pack 130. Asshown, the tabs 121 have a curvature which creates a chamfered edge thatengages the edges of the recesses 235. The shape of the tabs 121 and therecesses 235 are full complimentary, which creates the friction orcompressive retaining force between the pin 120 and power pack 130. Therelease pin 120 also includes downwardly projecting ribs 122 a and 122b, which are adapted to be received on the top surface of the power pack130. The ribs 122 a and 122 b increase the stability and rigidity of therelease pin 120. It is contemplated that additional ribs may beprovided. The release pin 120 includes an outwardly facing flat end 123having a peripheral ledge 124. The peripheral ledge 124 permits graspingof the release pin 120 by the user. The ledge 124 is sized to rest onthe end surface of the outer body 110 adjacent opening 111. The releasepin 120 includes a downwardly extending pin 125, which engages thecollet 430 of the power pack 130. When secured in place (i.e., prior toremoval of the release pin 120 and prior to actuation of theauto-injector 100), the pin 125 prevents the end of the collet 430 fromcompressing, which prevents actuation of the auto-injector 100. The end123 has a shape corresponding to the oval/elliptical shape of the outerbody 110.

As drown in FIG. 46, the inner surface of the outer body 110 iscontoured to receive the power pack 130, a cartridge container 140 and aneedle cover therein 150. Unlike many prior art needle covers, theneedle cover 150 is positioned between the container 140 and the outerbody 110 such that the user does not contact the cover 150 during theoperation, which could impede the deployment of the cover or cause adiaphragm within the cartridge to rupture prematurely. Additionally, themechanisms for locking and deploying the cover member are located withinthe outer body 110 and are thus protected against tampering and dirtingress. The outer body 110 includes a cartridge container retentionstep 112 formed on the inner surface near the end of the outer body 110adjacent the opening 111. A ledge 142 of the cartridge container 140abuts the retention step 112 to limit the downward movement of thecartridge container 140 within the outer body 110 once the auto-injector100 has been assembled such that the container can not be moved out ofopening 114. A plurality of power pack retention openings 113 a, 113 band 113 c are formed on at least one side of the outer body 110.Projections or teeth 238 on the power pack 130 are snap fit into theopenings 113. This snap fit prevents the removal of the power pack 130from the outer body 110 once installed in the outer body 110. The powerpack outer body 230 is not movable with respect to the outer body 110.The ledge 142 of the cartridge container 140 is sandwiched between theretention step 112 and the power pack 130.

An opening 114 is formed in the outer body 110 on an end opposite theopening 111. The opening 114 is configured such that a portion of thecartridge container 140, a portion of the needle cover 150 can extendtherefrom. The step 112 limits the travel of the container 140 throughopening 114. The end of the outer body 110 is intended to be orientatedadjacent the injection surface of the user such that end portion of thecover 100 contacts the injection surface.

The power pack 130 will now be described in greater detail in connectionwith FIGS. 17-20, 22-31 and 35-37. The power pack 130 includes a powerpack outer body 230, a power pack inner body 330, a collet 430, and apower pack spring assembly 530. The activation force necessary torelease the energy stored in the power pack is between 4 to 8 pounds.The activation force is the force required to release the collet 430from the inner body 330 when the auto-injector 100 is pressed againstthe injection surface. The injection force provided by the springassembly 530 is approximately 30 pounds. The injection force must besufficient such that the cartridge 160 is advanced within the cartridgecontainer 140 to drive the needle such that it pierces the sheath topermit injection of the medicament into the user. The power pack outerbody 230 is a generally cylindrical elongated hollow body 231. Aplurality of outer peripheral ribs 232 a, 232 b and 232 c extendoutwardly from an outer surface of the hollow body 231. While these ribs232 are shown, it is contemplated additional ribs may be provided. Theribs 232 are provided to prevent distortion of the outer body 110 of theauto-injector 100. A plurality of outer longitudinal ribs 233 a, 233 bare spaced about the outer surface of the hollow body 231. The ribs 233cooperate with the ribs 232 to further strengthen the auto-injector 100and prevent distortion of the outer body 110 when gripped and used by auser.

One of the peripheral ribs 232 a forms a top end surface 237 of thepower pack outer body 230. A hole 234 is provided in end surface whichis sized to receive the downwardly extending pin 125 of the release pin120. Retention recesses 235 a and 235 b are formed on opposing sides ofthe hollow body 231 adjacent the top end surface. The recesses 235 a and235 b are formed by walls 236 a and 236 b which extend outwardly fromthe hollow body 231 and upwardly from the top end surface 237 of theperipheral rib 232 a. The recesses 235 a and 235 b, are aligned with theside recesses 111 a and 111 b of the outer body 110 such that when therelease pin 120 is secured to the auto-injector 100, the tabs 121 a and121 b are received in both recesses 235 a and 235 b. The recesses 235 aand 235 b are sized to apply a compressive force on the tabs 121 a and121 b to secure the release pin 120 in place to prevent inadvertentremoval.

As shown in FIGS. 17, 26 and 27, the walls 236 a and 236 b extendupwardly from the end surface 237 of the peripheral rib 232 a. With suchan arrangement, the end surface 237 is spaced or recessed below the endsurface of the outer body 110, as shown in FIG. 26, forming a recess115. The recess 115 reduces and/or avoids the visual effect of a pushbutton. As such, the user will not be inclined to press the end surface237 to administer the medicament. Additionally, it provides a visualindication to the user that the recess 115 is located at the inoperativeend of the auto-injector 100 such that the user is inclined to place thecover 150 against the injector surface not the opposite end of theauto-injector. The recess 115 also serves to space the hole 234 from theend of the auto-injector 100 to deemphasize the presence of the hole 234such that it is hidden when the user reads the label on the outer body110. As such, the user is disinclined to position the hole 234 adjacentthe injection site. This arrangement is just one countermeasure providedto insure against improper use of the auto-injector 100. The ribs 122 aand 122 b of the release pin 120 are received within the recess 115.

A plurality of projections or teeth 238 a, 238 b, 238 c are formed onthe outer surface of the hollow body 231. The teeth 238 a, 238 b, 238 care sized to be snap fit into the openings 113 a, 113 b, 113 c to securethe power pack 130 within the outer body 110. This construction permitsthese components 110 and 130 to be secured together without the need ofan adhesive of other form of bonding. A corresponding set of teeth 218may be provided or the opposite side of the hollow body 230 to match thecorresponding openings in the outer body 110.

The interior of the hollow body 231 includes a recess 231 a, which issized to receive a retention tab 334 on the power pack inner body 330.The recess 231 a may be a groove, which extends about the innerperiphery of the hollow body 231. The recess 231 a is positioned in thehollow body 231 near an end opposite the end surface 237. As seen inFIGS. 1 and 28, a collet activation structure 239 extends into theinterior of the hollow body 231 from the inner side of the end surface237. The collet activation structure 239 has a generally cylindricalshape with a sloped collet activation surface 239 a located on a freeend. The activation surface 239 a is provided such that when the pin 120is removed and the front end of the injector is forced into an injectionsite so that cartridge container 140 rearwardly moves to engage innerbody 330, this will rearwardly force the arrowheads 434 and particularlyrearward surface 489 thereof (see FIG. 35) into engagement with surface239 a to force the arrowheads 434 of the collet 430 together to releasethe spring assembly 530 and thus release the necessary energy to injectthe medicament into the user. Ribs 239 b may be provided to reinforcethe collet activation structure 239. It is contemplated that other meansof releasing the collet 430 may be employed. A push button typeactuation arrangement may be employed, which is described in greaterdetail in U.S. Pat. No. 4,031,893 and hereby incorporated in itsentirety by reference.

The power pack inner body 330 is a generally cylindrical hollow innerbody 331. The hollow inner body 331 has an opening 332 formed in oneend. The opening 332 has a collet assembly lead-in surface 332 a whichis used to compress a portion of the collet assembly 430 during assemblyof the auto-injector 100 such that is can be properly mounted within thepower pack inner body 330. The opening 332 also has a collet retentionsurface 332 b located on an opposite edge which support the opposingarrowheads 434 of the collet 430 prior to activation. The hollow innerbody 331 has an opening 333 formed on an opposing end. Spaced from theopening 333 are a plurality of retention tabs 334 which are sized to besnapped into the retention recess 231 a. The recess 231 and tabs 334permit limited movement between the power pack inner body 330 and thepower pack outer body 230. The arrangement is also beneficial forpurposes of assembling the auto-injector 100. The inner body 330 and theouter body 230 can be preassembled. The recess 231 and tabs 334 maintainthe inner body 330 and the outer body 230 in proper alignment forassembly. Furthermore, this arrangement prevents the subassembly of theinner body 330 and the outer body 230 from separating prior to the finalassembly in the auto-injector 100. It is also contemplated that othermeans which permit limited movement between the outer power pack and theinner, power pack, which secure the components together may be employed.A ledge 335 at least partially extends about the periphery of theopening 333. The ledge 335 is sized to engage the cartridge container140 and the power pack outer body 230 at certain times during theoperation of the auto-injector 100, described in greater detail below. Aspacing exists between the inner power pack 330 and the cartridgecontainer 140 after assembly and prior to activation of theauto-injector 100 to create a gap, which avoids permanently puttingforces on the power pack and the spring 530.

A collet 430 is received within the hollow interior of the power packinner body 330. The collet 430 preferably is a molded one piececonstruction. The collect 430 has an elongated body 431 having anopening 432 formed therein which forms a pair of side arms 433 a and 433b. Each side arm 433 a and 433 b includes an arrowhead detail 434 a and434 b respectively. One side of each arrowhead 434 a and 434 b isconfigured to contact and engage the collet retention surface 332 b. Anopposite side of each arrowhead 434 a and 434 b is configured to engagethe collet assembly lead-in surface 332 a, which permits the side arms433 a and 433 b to be deflected inwardly to permit operation of theauto-injector 100. The end 435 of the collet 430 adjacent the arrowheads434 a and 434 b includes an opening 435 a sized to receive the pin 125of the release pin 120. The pin 125 prevents the side arms 433 frombeing deflected inwardly towards each other. When secured in place, thepin 125 prevents activation of the auto-injector 100. The opening 432has an arch 432 a formed on one end, as shown in FIG. 37. The arch 432 ahelps stabilize the side arms 433 and assist them in springing apartwhen the arms have been compressed together. The arch 432 a reduces theamount of stress on the collet.

The collet 430 is positioned within the power pack spring assembly 530.One end of the spring assembly 530 is supported on a flange 436 formedon the collet 430. The flange 436 extends outwardly from the elongatedbody 431. While the flange 436 supports one end of the spring assembly530, the location of the flange 436 on the body 431 can also serve todefine the delivered dose volume of medicament injected into the user.In certain applications it is desirable to control the amount ofmedicament delivered through the needle such that a portion of themedicament remains in cartridge 160. The flange 436 may limit thedistance that the collet 430 can travel into the cartridge 160, whichcontains the liquid medicament. As such, the amount of medicamentdelivered is controlled. In this arrangement, the flange 436 is sized tocontact the end of the cartridge 160. For larger diameter cartridges andfor larger doses of medicament, it is contemplated that the flange 436can travel within the cartridge 160. The collet 430 further includes aprojection 437, which receives a plunger 438. The plunger 438 isslidably received within the cartridge 160. In other applications, it isdesirable to dispense all of the medicament from the container 160. Asmall residual amount of medicament remains in the needle 162 and theneck of the cartridge 160 adjacent the needle 162. In theseapplications, the flange 436 travels within the interior of thecartridge 160 so that the plunger 438 travels the length of the interiorof the cartridge 160 to dispense all of the medicament (except for theresidual amounts mentioned above) through the needle 162. It iscontemplated that different sized collets 430 may be used in the presentauto-injector 100. As such, the collet 430 can be changed based uponcartridge size and desired dose.

The collet 430 is preferably formed as a single piece from a suitableplastic material. The one piece collet 430 simplifies manufacturing andlowers costs by reducing the number of components needed to form acollet. In conventional collets, multiple brass components may be used.In addition in other auto-injectors, a spacer has been required for usein conjunction with the collet 430 to accommodate different amounts ofmedicament for different auto-injectors. The collet 430 in accordancewith the present invention eliminates the multi component constructionand also advantageously eliminates the need for a spacer. The length ofthe collet can be selected based upon the desired dosage. Thisconstruction further permits the elimination of a metal insert typicallyfound in the plunger and a firing seat above the power pack inner body.It is contemplated that the size and shape of the collet 430 itself maybe varied to accommodate different sized cartridges 160. When the flange436 does not contact the cartridge 160, it is possible to dispense theentire contents of the cartridge 160 except for any residual amountsremaining in the needle or in the neck of the cartridge 160. It iscontemplated that a nipple plunger, as disclosed in U.S. Pat. No.5,713,866 to Wilmot, the disclosure of which is hereby incorporatedspecifically herein by reference, may be employed prevent any buildup ofresidual amounts of medicament in the neck of the cartridge 160. Theposition of the flange 436 can be varied to control the amount of dosageinjected into the user when the flange is positioned such that thecollet and the plunger 438 travel a greater distance within thecartridge 160 before the flange 436 contacts the cartridge 160, a largerdose is dispensed. The length of the collet 430 and the diameter of thecartridge 160 can be selected to control the flow of fluid through theneedle 162 of the cartridge 160 so that a desired flow rate is obtained.The auto-injector 100 in accordance with the present invention isconfigured such that collets 430 of varying sizes can be used within thesame outer body 110 and the power pack 430.

An opposite end of the spring assembly 530 rests against an innersurface of the power pack inner body 330 against opening 332.

The cartridge container 140 will now be described, in greater detail inconnection with FIGS. 41 and 49-52. The cartridge container 140 has agenerally elongated hollow body 141 sized to be received within theouter body 110. A ledge 142 is formed on one end of the elongated body141. The ledge 142 contacts the retention step 112 formed on the innersurface of the outer body 110. The ledge 142 limits the downwardmovement of the cartridge container 140 within the outer body 110 suchthat it cannot be removed through opening 114. The ledge 142 is formedby peripheral ribs 142 a and 142 b, which extend outwardly similar tothe ribs 232 a, 232 b and 232 c on the power pack outer body 230. Theribs 142 a and 142 b also prevent distortion of the outer body 110.

The elongated hollow body 141 has a hollow interior sized to receive thecartridge 160 therein. The hollow body has an opening 143 such that thecartridge 160 can be located in the hollow interior and to permit thecollet 430 to be slidably received within the cartridge 160. Thecartridge container 140 and the locking teeth 340 thereof are designedto accommodate various sized cartridges 160, while maintaining fillneedle cover functionality. As such, a common design needle coverassembly (including the cartridge container and locking teeth) can beused for various different volumes of drugs and different sized needles.For longer and larger cartridges, it is desirable to provide additionalsupport to prevent axial and radial movement, which could damage orfracture the cartridge 160. A pair of tabs 600 are formed on the hollowbody 141 to apply a compressive force on the cartridge 160 to hold andalign the cartridge 160 in a proper orientation to prevent such axialand radial movement. The tabs 600 provide friction to prevent movementof the cartridge 160 within the hollow body 141 during shock loading toprevent the cartridge from being dislodged or moved forward with thecartridge holder 140 prior to the medicament dispersing sequence.Typically, the smaller cartridges do not contact the tabs 600. Thecollet 430 and the needle and needle sheath provide sufficient supportfor the cartridge. The end of hollow body 141 has a tapered constructionwith an opening 144 sized to permit the passage therethrough of theneedle 162 and protective sheath 165 of the cartridge 160. A pluralityof ribs 145 are formed on the otter surface of the hollow body 141 onthe tapered end. The ribs 145 help stabilize the needle cover spring 153of the needle 150. The ribs 145 also serve as guides to aid in theassembly of the auto-injector 100.

The elongated hollow body 141 has at least one viewing window 141 a and141 b formed therein. The viewing windows 141 a and 141 b permit theuser to view the contents of the cartridge 160 before activation of theauto-injector 100 to insure that the medicament has not becomecontaminated or expired.

A pair of locking arms or wings 240 extend from the ledge 142 and areconnected to a mid-portion of the hollow body 141, as shown in FIG. 52.Each locking wing 240 has a thickened strut 241 having a generallycurved shape, as shown in FIG. 52. The thickened strut 241 is curvedsuch that when a compressive load is applied to the locking wing 240(e.g., when a user is attempted to push the needle cover 150 back intothe outer body 110 after use of the auto-injector 100) the thickenedstrut 241 bends in the manner illustrated by the dashed lines in FIG.52. With such a construction, the locking wings 240 are supported by thebody 141 of the cartridge container 140, which increases the compressivestrength of the locking wings 240. While not preferred, it iscontemplated that a single locking wing 240 can be provided.

A thinner strut 242 extends from the free end of the strut 241 and isconnected to the body 141 of the cartridge container 140. A lockingsurface 243 is formed at the intersection of struts 241 and 242. Thelocking surface 243 engages a surface on the cover 150 to limit theinward travel of the cover 150 after operation of the auto-injector 100,as shown in FIGS. 9 and 10. The thinner strut 242 provides a springforce to keep the thicker strut 241 biased in an outwardly direction.The thinner strut 242 also provides tensile strength under extreme loadsand helps prevent the strut 241 from collapsing in a sideways directionbecause the thinner strut 242 remained retained in a guide groove in theneedle cover 150 after the cover member 150 has moved to an extendedposition. The curved shape of the strut 242 permits the strut 242 tobend inwardly as shown in the dashed lines in FIG. 52. This prevents theentire wing 240 from forming a rigid arch. Thus allowing the thickerstrut 241 to flex inwardly towards the body 141 without causingexcessive compressive leads along the wing 240. It is contemplated thatthe locking arm 240 may be located on the outer body 110.

As shown in FIGS. 39, 41, 49, 50 and 52, the elongated body 141 of thecartridge container 140 includes a recess 244 located between thethinner strut 242. If the locking arms 240 are located on the outer body110, the recess 244 could be formed in the outer body 110.Alternatively, an opening in the outer body 110 could also be provided.This recess 244 increases the distance that the thinner strut 242travels inwardly toward the body 141, which increases the spring forceprovided to the thicker strut 241 to maintain the strut 241 in anoutwardly biased position. The locking wings 240 are normally maintainedin unstressed states. The locking wings 240 are compressed temporarilyas the needle cover 150 passes over them. The locking wings 240 springout such that the locking surface 243 engages the cover member 150 toprevent the needle cover 150 from being pushed backwards as shown inFIG. 10.

An elongated slot 146 is formed on each side of the elongated body 141.The slot 146 extends from the ends of the strut 242, as shown in FIGS.49 and 51. Each slot 146 is sized to receive a locking tooth 340. Asshown in FIGS. 1, 2, 4, 5, 7, 9, 16, 39 and 41, the locking teeth 340are locked on opposing sides of the cartridge container 140. The lockingteeth 340 are provided to hold back the needle cover 150 from deployinguntil after operation of the auto-injector 100. A pair of locking teeth340 are provided. Whale not preferred, it is contemplated that a singlelocking tooth 340 can be employed.

Each locking tooth 340 is capable of pivoting about the bearing axle 341within the axle slot 147. Multiple axle slots may be provided such thatthe position of the tooth 340 may be adjusted. As shown in FIGS. 56-59,each locking tooth 340 has a tab 342 having a bearing nice 342 a. Thetab 342 is positioned within the slot 146 such that it extends into theinterior of the elongated body 141 and is capable of contacting thecartridge 160. As the cartridge 160 is advanced within the body 141during operation of the auto-injector 100, the contact between thecartridge 160 and the bearing surface 342 a causes the locking tooth 340to rotate about the axle 341. While the surface 342 a contacts thecartridge 160, the locking teeth 340 have minimal or negligible impacton the movement of the cartridge 160 within the container 140 during theinjection operation. The low or minimal force applied by the lockingteeth to the cartridge is advantageous in that it does not buildpressure within the cartridge that could prematurely burst the diaphragmbefore the needle is fully extended. Furthermore, the movement of thecartridge 160 within the container 140 is not impeded or negligiblyimpeded by the locking teeth 340. The tab 342 extends from one side ofthe axle 341. A spring tail 343 extends from an opposing side of theaxle 341. The spring tail 343 is positioned within the slot 146 and isdesigned to slide along the cartridge container 140. The spring tail 343serves to bias the locking tooth 340 into a locked position such thatthe needle cover 150 is retained or locked in a retracted position priorto operation of the auto-injector 100. It is contemplated that thespring tail 343 may be replaced with a spring assembly. A bearingsurface 344 is provided on one end of the tail 343 to permit the springtail 343 to slide smoothly along the cartridge container 140 within slot146. The bearing surface 344 and central body 345 provide a flat areafor an ejector pin.

Formed below the spring tail 343 is a v-shaped notch 347. The notch 347has a locking surface 347 a on one side which holds the needle cover 150before activation of the auto-injector 100. Another surface 347 b limitsthe travel of the tooth 340 within the cartridge container 140 to limitits rotation. The notch 347 is formed as part of a tab 348, whichextends on either side of the spring tail 343. The locking teeth 340increase the flexibility of the auto-injector 100. Numerous, cartridgesof various lengths and diameters can be used without modifying theauto-injector 100. The spring action of the tails 343 adjust theposition of the locking teeth 340 such that the surface 342 a contactsthe cartridge 160.

The cartridge container 140 further includes, a pair of openings 141 aand 141 b, which are formed on opposing sides of the body 141. Theopenings 141 a and 141 b permit wing of the contents of the cartridge160 such that the user can visually inspect the medicament prior tooperation of the auto-injector 100. Prior to use the openings 141 a and141 b are aligned with corresponding openings in the needle cover 150such that the user can view the contents of cartridge 160 through theouter body 110. A ledge 149 having a plurality of reinforcing ribs 149 ais formed adjacent one end of the opening 141. The ledge 149 contactsthe edge 154 a of the opening 154 in the needle cover 150 to prevent theneedle cover 150 from moving any further forward relative to thecartridge container 140 so that the needle cover 150 cannot be pulledout of the outer body 110. When in this position, the locking surface243 of the locking wings 240 engages the end of needle cover 150 toprevent the needle cover 150 from being inserted back into the outerbody 110. When the ledge 149 is in contact with the edge of the openingin the needle cover 150, the openings in the cartridge container and theneedle cover are no longer aligned such that the user cannot view thecartridge 160 through the outer body 110. This provides a visual guideindicator to the user that the auto-injector 100 has been used.

The needle cover 150 will now be described in greater detail inconnection with FIGS. 12-15, 38, 42, 43 and 53-54. The needle cover 150has a generally elongated hollow body 151 having a shape that iscomplementary to the shape of outer body 110. The elongated body 151 isslidably received within the outer body 100. One end of the hollow body151 is tapered having an, enclosed end surface 152. End surface 152prevents a human finger (e.g., child's finger) from entering the needlecover and contacting the needle. End surface 152 has an opening 152 asized to permit the passage of the needle of the cartridge 160 therethrough during an injection operation, as shown in FIGS. 7 and 8. Theend surface 152 is intended to be placed on the injection surface of theuser during operation of the auto-injector 100 A needle cover spring 153is compressed between the end surface 152 of the needle cover 150 andthe cartridge container 140, as shown in FIGS. 1, 2, 4, 5, 7, and 9. Theauto-injector 100 with needle cover 150 in accordance with the presentinvention is designed to function like auto-injectors without needlecovers in that a similar activation force is required to operate theauto-injector. As such, the spring 153 has a very low load. The biasingforte for the cover 150 is less than the activating force of theauto-injector 100. The maximum load for the spring 153 is preferably 1.5pounds. The load is lower than the activation force (1.5 versus 4-8)necessary to actuate the auto-injector 100 such that the needle cover150 does not impact the operation of the auto-injector 100 when comparedto injectors without, covers such as disclosed in the '893 patent. Theribs 145 on the cartridge container 140 act to stabilize the spring 153within the cover 150. The hollow body 151 may include indents 151 a,shown in FIGS. 53 and 54. The indents 151 a reduce the thickness of theplastic to conserve materials.

The hollow body 151 further includes a pair of openings 154 formedthereon. As discusses above, the openings 154 align with the openings141 a and 141 b in the cartridge container 140 prior to activation toallow visibility of the medicament within the cartridge 160. Edgesurface 154 a of the opening 154 is designed to contact ledge 149 toprohibit further advancement of the needle cover 150.

Slots 155 are provided on opposing sides of the needle cover 150. Theslots 155 are positioned to be aligned with the locking wings 240 andthe locking teeth 340. The slots 155 guide and support the locking wings240 prior to deployment of the needle cover 150. A cross slot 155 a maybe provided to aid in the assembly of the auto-injector 100 such thatthe locking teeth 340 can be inserted in place on the cartridgecontainer 140 through slot 155 in the needle cover 150. Bearing surface344 can be placed through the slot 155 a. Locking projections 156 extendinwardly into the slot 155. The locking projections 156 are configuredto engage the locking surface 347 a on the locking teeth 340. Multipleprojections 156 are provided to correspond to the multiple axle slots147 in the cartridge container 140 for the bearing axle 341.

An interior groove 157 is provided within the interior of the hollowbody 151. The interior groove 157 is axially aligned with the slots 155.A portion of the strut 241 is aligned in the groove 157 when the covermember 150 is in the position shown in FIGS. 12 and 13. The grooves arealigned with the locking wings 240 to provide support and preventsideways collapsing of the locking wings 240.

The cartridge 160 includes a generally elongated glass tube having anopening 161 at one end sized to receive the plunger 438 and collet 430.The flange 436 on the collet 430 is designed to contact the end of thecartridge 160 to limit the inward travel of the plunger and collet intothe cartridge 160 to control the dosage dispensed through the needle162. The needle 162 is attached to a hub assembly 163 which is securedto another end of the cartridge 160. The hub assembly 163 may include adiaphragm 164 to prevent the passage of liquid medicament through theneedle 162 prior to activation of the auto-injector. The needle 162 isencased in a protective sheath 165. The sheath 165 is secured to the hubassembly 163. The needle 162 pierces the sheath 165 during operation,when the needle 162 projects through the needle cover 150. The cartridge160, as illustrated, provides a container for a dose of liquidmedicament. It is not intended that the auto-injector 100 be limitedsolely to the use of a single liquid, rather, it is contemplated thatone or more liquids may be stored in cartridge 160 that mix uponactivation of the auto-injector 100. Furthermore, a solid medicament anda liquid can be separately stored in the cartridge 160 whereby the solidis dissolved in the liquid prior to dispensing.

The operation of the auto-injector 100 will now be described in greaterdetail. The auto-injector 100 is showman an unactivated state in FIGS.1, 2 and 3. The release pin 120 is secured in place such that the pin125 is received within the hole 234 and the hole 435 a in the collet 430such that the side arms 433 can not be inwardly deflected. In thisposition, the needle cover 150 is held in a locked retracted position bythe locking teeth 340. The locking surfaces 347 a are biased by thespring tails 343 into alignment with the locking projections 156 on theneedle cover member 150. In this position, the auto-injector 100 cannotbe operated and the needle 162 is not exposed.

When operation of the auto-injector 100 is desired, the release pin 120is grasped by the peripheral ledge 124 and pulled to remove the releasepin 120 from the end of the auto-injector 100. This readies theauto-injector 100 for operation, as shown in FIG. 4. The arrowheads 434a and 434 b and side arms 433 a and 433 b are now capable of beingcompressed together when the auto-injector 100 is activated. The lockingwings 240 are not compressed or stressed at this time.

As shown in FIGS. 5 and 6, the user presses the end surface 152 of theneedle cover 150 against the injection site. This causes thepre-compressed spring 153 to be slightly further compressed until theneedle cover 150 moves and contacts the front end 145 a of the cartridgecontainer 140 (see FIG. 51), thus moving the ledge 142 of the cartridgecontainer 140 rearwardly. The force of spring 153 is less that the forceof spring 530. The needle cover 150, the cartridge container 140 and thecartridge 160 are then moved rearwardly in to the outer body 110. Thecartridge container 140 moves upward into the outer body 110 until theledge 142 thereof contacts the ledge 335 of the power pack inner body330. The power pack inner body 330, and the collet 430 and the springassembly 530 are then pushed rearwardly in the auto-injector 100 intothe power pack outer body 230. The collet 430 moves upwardly until itcontacts the collet activation structure 239, shown in FIG. 28. Thearrowheads 434 a and 434 b contact the sloped activation surface 239 a.The arrowheads 434 a and 434 b are compressed together by the slopedsurface 239 as the collet 430 moves rearwardly, such that the arrowheads434 a and 434 b contact the sloped activation surface 239 a. Thearrowheads 434 a and 434 b are compressed together by the sloped surface239 as the collet 430 moves rearwardly, such that the arrowheads 434 aand 434 b are released from the collet retention surface 332 b. Duringthis loading operation, the needle cover 150 is rearwardly pushed asmall amount into outer body 110. When this occurs, the preload on thelocking teeth 340 provided by the spring 153 is temporarily removed. Assuch, the v-shaped notch 347 temporarily disengages projection 156formed on the needle cover 150. During this operation, the projection156 no longer contacts either surface 347 a or 347 b, but remains in aspace provided between the surfaces. As such, when pressure from theneedle cover 150 is removed, the projection 156 will return into contactwith the surfaces 347 a or 347 b, but remains in a space providedbetween the surfaces. As such, when pressure from the needle cover 150is removed, the projection 156 will return into contact with thesurfaces 347 a and 347 b. The locking teeth 340 will completely releasethe needle cover 150 only in response to movement of the cartridge 160as it travels forwardly within the cartridge container 140. Accordingly,the needle cover 150 cannot deploy until the cartridge 160 moves.

The spring 530 and collet 430 simultaneously force the cartridge 160 andthe cartridge container 140 forward toward the open front end of theouter body 110. Once the needle 162 has been extended through the needlecover 150, pressure of the medicament within the cartridge 160 causesthe diaphragm 164 to burst permitting the flow of medicament into theuser. The drug is forced through the needle 162 allowing the plunger 438and collet 430 to move further into the cartridge 160. The cartridgecontainer 140 retains the sheath 165 and also prevents the spring forceof the spring 530 from being transferred through the cartridge 140 ontothe needle cover 150 and the injection site. That is, force from spring530 that drives the cartridge 160 forward is opposed by the front end ofthe cartridge container 140, with the sheath 165 compressed therebetween, rather than force being received directly by the needle cover150. In addition, the needle cover spring force is less than theactivation force required to collapse the collet to release the colletduring actuation. Preferably, the needle cover spring force is about0.25 to 0.75 of the minimum activation force. The power pack residualspring force after activation is contained within the cartridgecontainer 140, cartridge 160, the outer body 110 and the power packouter body 230. This arrangement advantageously prevents a kickbackeffect from occurring. As such, the auto-injector is not pushed awayfrom the injection site during activation to ensure that the proper doseof medicament is administered and the proper needle extended length orproper needle penetration is maintained. This effect would occur if thespring force from the spring 530 were transferred to the needle cover150 and the injection site, whereby the auto-injector 100 could bepushed away from the injection site and alter the location of the needle162 within the injection site. This has several negative impactsincluding startling the patient; changing the injection from anintramuscular to subcutaneous injection, which will affect pk levels. Atthe same time, the cartridge 160 is advanced within cartridge container140 (i.e., when the needle 160 goes from a retracted position toextended position). The advancement of the cartridge 160 causes thelocking tooth 340 to pivot about the axle 341. This is in response tocartridge 160 contacting bearing surface 342 a and pushing the bearingsurface 342 a away from the main longitudinal axis of the needle 162.This rotation of the locking tooth 340 causes the locking surface 347 ato disengage the locking projections 156. The surface 347 b limits therotation of the locking tooth 340. At this point, the needle cover 150is in an unlocked position such that it can move with respect to thecartridge container 140. The release of the collet 430 from the colletretention surface 332 b forces the end of the power pack inner body 330into contact with the power pack outer body 230.

Once the dose has been injected into the user, the user removes theauto-injector 100 from the injection surface. Since the needle cover 150is not locked with respect to the cartridge container 140, the spring153 forces the needle cover 150 out of the outer body 110 to cover theexposed needle 162, as shown in FIGS. 9 and 11. Since the slot 155 isaligned with groove 157 and a portion of the strut 241 is retained inthe slot 157, the portion of the strut 241 moves into the groove 157when the cover 150 moves outwardly. As the needle cover 150 slidesoutwardly, the locking wings 240 are temporarily compressed by theneedle cover 150 as the thicker strut 241 slides through the groove 157.This compression occurs when the bottom surface of the groove 157contacts the top surface of the strut 241. The wings 240 compress in themanner shown in the dashed lines in FIG. 52. Once the thicker strut 241clears the groove 157 such that the wings 240 and needle cover 150 arein the position illustrated in FIGS. 10, 14 and 15, the locking surface243 contacts the end of needle cover 150 to prevent the needle coverfrom being reinserted into outer body 110. In the event that inwardforce is applied, the struts 241 and 242 compress such that the lockingwing 240 is pressed against the body 141 of the cartridge container 140such that the surface 243 remains engaged with the needle cover 150.This arrangement limits the inward travel of the needle cover 150. Theledge 149 engages the edge 154 a of the opening 154 in the needle cover150. The auto-injector 100 is now in an inoperable stored position.

Safe user operation of the auto-injector is of paramount importance.Various features were tested and studied in user trials to improvesafety and usability. One feature in particular, color coding of someinjector parts with certain colors, was shown to minimize, if noteliminate, the potential for accidental injection caused by incorrectlyorienting the auto-injector. That is, after removing release pin 120,some users mistakenly placed the auto-injector upside down against aninjection site, which would have likely resulted in the accidentalinjection of a thumb or other finger. The user trials indicated that,surprisingly, a blue release pin 120 and an orange needle cover 150 (asopposed to other colors, such as, for example, a green release pin and ared needle cover) best reduced the number of incorrect injectororientations and accidental injections. User trials also indicated thatlabeling of the needle cover improved injector handling, safety, andusability. For example, needle covers with “NEEDLE END” printed near thetip of the cover, as shown in FIG. 60, and “USED” printed farther up onthe needle cover that only became visible after the auto-injector wasused, as shown in FIG. 61, prevented incorrect injector orientation,accidental injection, and attempted use of a discharged auto-injector.

The invention having been disclosed in connection with the foregoingembodiment and examples, additional variations will now be apparent topersons skilled in the art. Various modifications and variations to theabove described auto-injector can be made without departing from thescope of the invention. The invention is not intended to be limited tothe embodiment specifically mentioned and accordingly reference shouldbe made to the appended claims rather than the foregoing discussion ofpreferred embodiments and examples to assess the spirit and scope of theinvention in which exclusive rights are claimed.

We claim:
 1. An auto-injector comprising: a housing; a cartridgecontainer disposed within the housing; a cartridge received within thecartridge container, the cartridge having at least one opening thereinand containing a medicament, the medicament rearwardly confined by aplunger, the cartridge including a needle assembly to dispense themedicament there through, the needle assembly having a needle; anactuation assembly having a stored energy source capable of beingreleased to drive the plunger within the cartridge to dispense themedicament through the needle assembly; and a needle cover receivedwithin the housing, the needle cover having an opening formed therein topermit passage of the needle there through during a medicamentdispensing operation, the needle cover having a first locked positionwherein the needle cover is in a locked retracted position prior toactivation of the auto-injector, the needle cover having a second lockedposition wherein the needle cover is in a locked extended position afterthe medicament dispensing operation, the needle cover surrounding theneedle on all sides outside of the housing to prevent contact with theneedle before activation of the auto-injector and after the medicamentdispensing operation; wherein the cartridge further comprises a needlesheath disposed about the needle, the needle sheath being compressedbetween the cartridge container and the cartridge during the medicamentdispensing operation.